Method for welding metallic gauze



Jan. 1, 1963 R. T. WILLIAMS ETAL 3,070,878

METHOD FOR WELDING METALLIC GAUZE Original Filed Jan. 21, 1958 FIGJINVENTORS RALPH r. WILLIAMS DOUGLAS w. ELEY KM ALL-r AT RNEYS 4 nitedStates Patent 2 3,070,878 Patented Jan. 1, 1963 3,070,878 METHOD FORWELDENG METALLIC GAUZE Ralph T. Williams, Toronto, Ontario, and DouglasW.

Eley, Willowdale, Ontario, Canada, assignors to Engelhard Industries ofCanada Limited, Toronto, Ontario, Canada, a corporation of OntarioOriginal application Jan. 21, 1958, Ser. No. 710,273.

Divided and this application May 25, 1959, Ser. No-

6 Claims. c1. 29-419 This invention relates to a welding method and,more particularly, relates to a welding method for welding the warp andweft strands of metallic gauze.

Metallic gauze, such as platinum gauze for example, is extensively usedfor many industrial applications, such as a catalytic material for theproduction of hydrogen peroxide. One such metallic gauze consists ofplatinum, or platinum alloy, warp and weft strands and the gauze mayhave 22 warp strands, equidistantly spaced and having a total width of 1inches. The weft strands are equidistantly spaced seven to the inch, andthe platinum strands may have a diameter of the order of 0.0048 inch. Itis necessary to weld the warp and weft strands at each intersection inthe gauze, and it is necessary that this welding be accomplished bymeans which is rapid in operation in order that the heat imparted to thegauze is not removed therefrom by the welding apparatus, and in thisconnection it has been found that welding devices which incorporaterolls, through which the gauze is passed, are completely unsuitable dueto the fact that the rolls conduct away an excessive amount of heat andthe desirable welding characteristics are not obtained.

In accordance with the present invention, an automatic welding device isprovided for the welding of metallic gauze, such as platinum gauze, forexample, in which the welding operation is effected in a substantiallyinstantaneous manner, the welds being effected by means of an impactdevice which does not conduct away excessive heat from the preheatedgauze, and thereby effects strong uniform welds at all of theintersections of the warp and weft strands of the gauze material.

The platinum gauze or tape to be welded is woven on a conventionalweaving machine which can be used to weave either cloth or fine metallicstrands. In the weaving process, the gauze is interwoven with cottonfibres, and upon leaving the loom, the gauze is maintained underconstant tension and the cotton fibres are ignited, thus leaving theplatinum braid, or gauze, exposed. The platinum gauze or braid is thenpreheated by any suitable means, such as a gas flame, electricalresistance, or high frequency induction, to a dull red heat and is thenpassed through a pulsating air hammer which effects the desired weldingof the warp and weft strands. The instantaneous application of pressureobtained by the air hammer technique, permits the wire intersections tobecome welded, since the action of the air hammer is sufficiently rapidto eiiminate the dissipation of heat from the gauze or braid to thehammer. The air hammer could, of course, be replaced with any similarhammer means such as an electric hammer, or a mechanically actuatedhammer, or the like.

Before passing the braid through the air hammer, it is necessary thatthe braid be preheated to a temperature such that the desired Welds canbe obtained by impact and thus the gauze is preheated to a temperaturein the range of about 1700 to 1900 F. The gauze may be passed throughthe air hammer at the rate of about 0.5 to 2.0 feet per minute, and iswelded by means of the impact hammer, the blade of the hammer pulsatingat the rate of 3500 to 9000 strokes per minute, preferably about 5000strokes per minute. It is, of course, possible to feed the gauze throughthe hammer at any desired rate, providing the action of the movableblade on the hammer is sufficiently rapid that all of the intersectionsof the warp and weft strands are subjected to the impact of the hammerso that each joint receives a strong uniform weld.

Referring to the accompanying drawings in which one embodiment of thewelding apparatus of the present invention is shown,

FIGURE 1 is a view in elevation of the welding apparatus showing thetensioning roll removed,

FIGURE 2 is a plan view of the apparatus of FIGURE 1, showing the gauzeremoved therefrom,

FIGURE 3 is an end view of the apparatus of FIGURE 1, with the end rollremoved,

FIGURE 4 is a detailed view in elevation of the air hammer employed, and

FIGURE 5 is a side view of the air hammer shown in FIGURE 4. Referringto FIGURE 1 of the drawings, the device includes the frame members 2,which may be fabricated, if desired, from angle iron, having thereinforcing webs 4- secured thereto by any suitable means such aswelding. A base member 6 is secured to the top of the frame whichsupports a pair of guides 8 and 10, which may be made of cold rolledsteel, if desired, these guides forming a track upon which is-mountedthe roll supports 12 and 14 which support the guide rolls 16 and 18respectively. The guides 8 and 10 also support the welding head 20. Theroll supports 12 and 14 and the welding head 20 may be locked in anydesired position on the guides 8 and 10 by means of the set screws 22.

A roll support 24 is mounted on the left-hand end of the base 6 andsupports the guide roll 26 near the upper end thereof. The platinum tapeor gauze 28 to be welded, passes beneath the roll 26 and beneath, andout of contact with, a /s" standard T 30 having holes drilled in thebottom thereof. The T is mounted on a pipe 32, shown in FIGURE 2, thepipe 32 being secured to the frame 6 by any suitable means such as thesupport member 34, the pipe 32 being connected at its lower end to asource of air under pressure, not shown.

A plate 36 is secured to the guide member 10 and supports a vertical arm38 having the cross arm 40 connected thereto, the cross arm 40supporting a gas burner 42 having a rectangular burner head 44 thereon,the burner head being of sufficient width so that the tape or gauze 28passing above is completely and uniformly heated by the gas flameissuing from the burner head 44. A suitable combustible mixture of airand a gas, such as natural gas, methane, propane or acetylene gas, ispassed into the burner 42' through the hose 46, air and gas being passedinto the Y connection 48 from suitable sources, not shown.

The welding head 20 is secured to the guides 8 and 10 by any suitablemeans such as set screws, and includes the plate members 50 and 52, bestseen in FIGURES 4 and 5, which serve to support the upper fixed blade 54therebetween, and the movable spring loaded blade 56, the springs 58tending at all times to divert the lower movable blade away from thefixed upper blade. The lower blade is actuated by means of a rod 60which is connected to a piston, not shown, within the cylinder 62. Inthe embodiment shown, the cylinder is a conventional pin riveter havinga piston travel of /8 inch.

All parts of the welding head other than the welding blades may befabricated from cold rolled steel, if desired, while the bladesthemselves may be fabricated from hardened tool steel. When weldingplatinum wire having a diameter of 0.0048 inch, the blades may have aclearance when closed of 0.004 inch.

Air is supplied to the cylinder 62 through a suitable 3. conduit 64which is connected to any suitable source of air under pressure, notshown.

A guide roll 66 is mounted on the right-hand end of the base member 6,and is supported by means of the roll supports 68, and the finishedgauze is wound on a drum 70 which is supported on the frame members 2 bythe shaft 72 which is mounted in the shaft hangers 74. The finishedwelded gauze is wound on the drum 70, interleaved with the paper 75,which is fed from the roll 76 and over the guide roll 78.

A tensioning device is also used to exert a constant tension on thegauze being Welded, the tensioning device consisting of the drum 80which is keyed to the shaft 72. The drum 80 has a cord or cable 82 woundthereon which passes over a pulley 84 and has the counterweight 86secured to the free end thereof, whereby the counterweight acts to exerta tension on the gauze being wound on the spool 70.

In the operation of the device of the invention, the platinum braid orgauze, being interwoven with cotton fibres, is passed from the loombeneath the roll 26, and as soon as the braid has passed beneath theroll 26, the cotton fibres are ignited by means of a gas burner orsimilar igniting device, not shown. The braid then passes beneath thedrilled T 30 and the air blast issuing from the drilled T serves toremove all cotton ashes from the gauze. The gauze then passes over theroll 18 and over the burner head 44, which uniformly heats the gauze toa dull red heat, after which the heated gauze passes through the weldinghead 20 and is impact Welded between the fixed blade 54 and the movableblade 56. The welded gauze then passes over the guide rolls 16 and 66,and is wound on the drum or spool 70, being interleaved with a paperstrip 75. Tension is maintained at all times on the gauze being weldedby means of the drum 80, the cord 82, and the counterweight 86.

The device of the invention thus provides an automatic means for thewelding of metal gauzes, and while the device has been describedparticularly in connection with the welding of platinum braid or gauze,it obviously is applicable to the welding of many other similarmaterials.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

This application is a division of copending application Serial No.710,273, filed January 21, 1958.

What is claimed is:

1. A method for welding metal gauze comprising moving the gauze relativeto the opposed blades of a reciprocating hammer, applying heat to themoving gauze to raise its temperature to within the range of about 1700F. to 1900 F., and rapidly hammering the gauze at a rate of 3500 to 9000strokes per minute immediately following the application of heat over anarrow area extending transverse to the direction of movement of thegauze.

2. A method for welding metallic gauze comprising the steps of movingthe gauze relative to the opposed blades or a reciprocating hammer,raising the temperature of the gauze to a dull red heat Within thetemperature range of about F. to 1900" F., and rapidly hammering thegauze at a rate of 3500 to 9000 strokes per minute over a narrow areaextending transverse to the direction of movement of the gauze beforethe gauze cools down appreciably.

3. A method for welding metallic gauze comprising steps of moving thegauze relative to the opposed blades of a reciprocating hammer, heatingthe gauze to a tem peratu're within the range of about 1700 F. to 1900 1and hammering the gauze at a rate of 3500 to 9000 strokes per minuteover a narrow area extending transverse to the direction of movement ofthe gauze immediately following the application of heat.

4. A method for forming welded metallic gauze comprising interweavingmetal strands and combustible fibers into a metallic gauze, burning thecombustible fibers included in the metallic gauze, removing the burnedfibers from the gauze, heating the gauze to a dull red heat within thetemperature range of about 1700 F. to 1900 F., and hammering the gauzeat a rate of 3500 to 9000 strokes per minute over a narrow areaextending transverse to the direction of movement of the gauze beforethe gauze cools appreciably.

5. A method for welding a metallic gauze which is interwoven withorganic fibers, which comprises igniting the fibers in moving metallicgauze, removing ashes of the fibers from the gauze, heating the movingmetallic gauze to a welding temperature, and very rapidly hammering themoving gauze before the gauze cools down appreciably over a narrow areaextending transverse to the direction of movement of the gauze, thehammering being sufficiently rapid to weld the metallic gauze.

6. A method for welding metallic gauze which comprises heating metallicgauze to raise its temperature to a welding temperature, and veryrapidly hammering the metallic gauze while moving before the gauze coolsdown appreciably over a narrow area extending transverse to thedirection of movement of the gauze, the hammering eing sufficientlyrapid to weld the metallic gauze.

References Cited in the file of this patent UNITED STATES PATENTS854,099 Mead May 21, 1907 943,438 Mead Dec. 14, 1909 949,860 Taylor Feb.22, 1910 1,489,153 Robinofl Apr. 1, 1924 2,122,604 Bridges July 5, 19382,178,633 Hooper Nov. 7, 1939 2,572,956 Servis Oct. 30, 1951 2,648,792Wylie Aug. 11, 1953

1. A METHOD FOR WELDING METAL GAUZE COMPRISING MOVING THE GAUZE RELATIVETO THE OPPOSED BLADES OF A RECIPROCATING HAMMER, APPLYING HEAT TO THEMOVING GAUZE TO RAISE ITS TEMPERATURE TO WITHIN THE RANGE OF ABOUT 1700*F. TO 1900* F., AND RAPIDLY HAMMERING THE GAUZE AT A RATE OF 3500 TO9000 STROKES PER MINUTE IMMEDIATELY FOLLOWING THE APPLICATION OF HEATOVER A NARROW AREA EXTENDING TRANSVERSE TO THE DIRECTION OF MOVEMENT OFTHE GAUZE.